Fences are one of the most effective measures to prevent and control wind-blown sand disasters,and the blocking effect of fences is largely determined by their porosity and height(H).This study employed wind tunnel ex...Fences are one of the most effective measures to prevent and control wind-blown sand disasters,and the blocking effect of fences is largely determined by their porosity and height(H).This study employed wind tunnel experiments to measure wind velocities on both sides of wire mesh sand fences with porosities of 75%,63%,56%,36%and heights of 10,5 and 2 cm.The effects of porosity and height on the blocking effect of the fences were evaluated on the basis of velocity variability,flow field,and the wind velocity reduction coefficient.Results show that the smaller the porosity,the stronger the blocking effect.The fence with a porosity of 36%had the strongest windproof efficiency of 0.70 and longest protection range of 9 H,and thus showed the best applicability in preventing and controlling wind-blown sand disasters.The fence with a porosity of 56%showed a windproof efficiency of 0.31 and a protection range of 7 H,which could be considered for adoption.However,fences with porosities of 75%and 63%were not recommended to be adopted,because their windproof efficiency and protection range were very small.Overall,the higher the fence,the stronger the blocking effect.The highest fence(10 cm)had the longest protection range of 90 cm,which was the best in application.Nevertheless,the 5 and 2 cm fences were almost consistent with 10 cm fence in windproof efficiency,which was still suitable for wind and sand fixation.展开更多
To research techniques for removing the water blocking effect caused by hydraulic applications in coal seams,the use of surfactants is proposed,based on the mechanics of the water blocking effect.Centrifugal experimen...To research techniques for removing the water blocking effect caused by hydraulic applications in coal seams,the use of surfactants is proposed,based on the mechanics of the water blocking effect.Centrifugal experiments were used to validate the effects of using surfactants;the results show that after dealing with vacuum saturation with water,the volume of micropores decreases,which results in a larger average pore size,and the volume of transitional pores,mesopores,macropores and total pores increases.Based on the distribution of pore size,the operation mode of ‘‘water infusion after gas extraction,then continuing gas extraction" is recommended to improve the volume of coal mine gas drainage.When the reflectance of vitrinite in coal samples is less than 1,using the surfactants Fast T,1631,APG,BS can mitigate the damage caused by the water blocking effect.But when the reflectance of vitrinite is larger than 1.4,the damage caused by the water blocking effect can be increased.When the surfactant CMC is used in hydraulic applications,the capillary forces of coal samples are almost negative,which means the capillary force is in the same direction as the gas extraction.The direction of capillary forces benefits the gas flow.So,using CMC can play an active role in removing the water blocking effect.Centrifugal experiments confirm that using CMC can effectively remove the water blocking effect,which has a beneficial effect on improving the gas drainage volume.展开更多
[ Objective] To investigate the blocking effects of spleen vaccine on vertical transmission of classical swine fever virus （CSFV） in sows. [ Method] Sows infected by CSFV were selected from three large-scale pig far...[ Objective] To investigate the blocking effects of spleen vaccine on vertical transmission of classical swine fever virus （CSFV） in sows. [ Method] Sows infected by CSFV were selected from three large-scale pig farms and they were randomly divided into group Ⅰ, group Ⅱ and control group. The sows in the group Ⅰ were vaccinated with CSF spleen vaccine at a 1.5 times normal dose per pig; those in the group Ⅱ were vaccinated with CSF spleen vaccine at a 2.0 times normal dose per pig; and those in the control group were vaccinated with cell vaccine at a 4.0 times normal- dose per pig. The CSF antigens of piglets were detected by enzyme-linked immunosorbent assay （ELISA）. [ Result] The antigen positive rate of piglets in the experimental group （18.5%） was significantly lower than that in the control group （48.1% ）. No significant difference was found be- tween the group Ⅰ and the group Ⅱ. [ Condmion] CSF spleen vaccine has good blocking effects on vertical transmission of CSFV in sows.展开更多
Phenolic acids (PAs) are widely found in many daily consumed vegetables and fruits.The inhibitory effects of PAs on Nnitrosomorpholine (NMOR) formation in vitro undersimulated gastric juice condition were studied. The...Phenolic acids (PAs) are widely found in many daily consumed vegetables and fruits.The inhibitory effects of PAs on Nnitrosomorpholine (NMOR) formation in vitro undersimulated gastric juice condition were studied. The results showed that the inhibjtoryIX)tency of thirteen varieties of PAs differed greatly, which may be related to theirchemical structures; the blocking rate (BR) of different killds of PAs were as follows:caf feic acid, 92.5%; tannic acid, 90.0%; gallic acid, 86.8%; sinaPinic acid, 86.2%; ferulicacid, 8l.l%; chlorogenic acid, 69.4%; gentisic acid, 69.2%; syringic acid, 62.1%; protocatechuic acid, 56.0%; p-coumaric acid, 52.5%; vannilic acid, 35.4%; moreover,p-hydroxybenzoic acid and m-coumaric acid had the least blocking effect or even slightcatalyzing effect. The results also demonstrated that amounts of NMOR formed werenegatively correlated with molar ratio of PAs to nitrite and that the optimum pH forinhibition was between 2 and 3.展开更多
BACKGROUND: It has been shown that although brain does not contain lining endothelial lymphatic vessel, it has lymphatic drain. Anterior lymphatic system of lymphatic vessel in brain tissue plays a key role in introdu...BACKGROUND: It has been shown that although brain does not contain lining endothelial lymphatic vessel, it has lymphatic drain. Anterior lymphatic system of lymphatic vessel in brain tissue plays a key role in introducing brain interstitial fluid to lymphatic system; however, the significance of lymphatic drain and the effect on cerebral edema remains unclear. OBJECTIVE: To investigate the effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats. DESIGN: Randomized controlled animal study. SETTING: Institute of Cerebral Microcirculation of Taishan Medical College and Department of Neurology of Affiliated Hospital. MATERIALS: A total of 63 healthy adult male Wistar rats weighing 300-350 g were selected in this study. Forty-seven rats were used for the morphological observation induced by lymphatic drain and randomly divided into three groups: general observation group (n =12), light microscopic observation group (n =21) and electronic microscopic observation group (n =14). The rats in each group were divided into cerebral lymphatic block subgroup and sham-operation control subgroup. Sixteen rats were used for observing the effect of cerebral lymphatic block on cortical evoked potential, in which the animals were randomly divided into sham-operation group (n =6) and cerebral lymphatic block group (n =10). METHODS: The experiment was carried out in the Institute of Cerebral Microcirculation of Taishan Medical College from January to August 2003. Rats in cerebral lymphatic block group were anesthetized and separated bilateral superficial and deep cervical lymph nodes under sterile condition. Superior and inferior boarders of lymph nodes were ligated the inputting and outputting channels, respectively, and then lymph node was removed so as to establish cerebral lymphatic drain disorder models. Rats in sham-operation control group were not ligated the lymphatic vessel and removed lymph nodes, and other operations were as the same as those in cerebral lymphatic block group. Morphological changes of the brain and alterations of latency of cortical evoked potential were detected on the 1st, 2nd, 3rd, 5th, 7th, 10th and 15th days after operation under general, light microscope and electronic microscope observations. MAIN OUTCOME MEASURES: ① Cerebral morphological changes; ② latent changes of cortical evoked potential. RESULTS: A total of 63 rats were involved in the final analysis. ① Cerebral morphological changes: General observation showed that, for cerebral lymphatic block rats, the surface of brain was pale and full, and cerebral gyrus was wide and flattened sulci after cerebral lymphatic block; and cerebral tissue space prolongation, increased interstitial fluid, neuronal degeneration and necrosis, diffused phagocytes and satellitosis were observed under light microscope. Neuronal swell and necrosis, glial cell swell, apparent subcellular changes such as mitochondron were observed under electronic microscope. ② Latent changes of cortical evoked potential: As compared with sham-operation control group, latency of cortical evoked potential in cerebral lymphatic blockage group prolonged on the 5th day and 7th day after cerebral lymphatic block [(6.28±0.23), (6.97±0.35) ms; (6.23±0.22), (7.12±0.20) ms; P < 0.01]. CONCLUSION: ① Cerebral lymphatic block plays an important role in cerebral morphology, and may result in abnormality of sensitive impulse conduction and prolong latency of cortical evoked potential. ② Examination of cortical evoked potential is easy and convenient, so it is regarded as a key index for lymphatic disturbed cerebral injury.展开更多
In this paper, blocking in response surface for fitting first order model incorporating neighbour effects has been investigated. The conditions for orthogonal estimation of the parameters of the model have been obtain...In this paper, blocking in response surface for fitting first order model incorporating neighbour effects has been investigated. The conditions for orthogonal estimation of the parameters of the model have been obtained. A method of constructing designs which ensures the constancy of variance of the parameter estimates of the model has also been given.展开更多
In GaN-based green light-emitting diodes（LEDs） with and without Mg-preflow before the growth of p-Al GaN electron blocking layer（EBL） are investigated experimentally.A higher Mg doping concentration is achieved in...In GaN-based green light-emitting diodes（LEDs） with and without Mg-preflow before the growth of p-Al GaN electron blocking layer（EBL） are investigated experimentally.A higher Mg doping concentration is achieved in the EBL after Mg-preflow treatment,effectively alleviating the commonly observed efficiency collapse and electrons overflowing at cryogenic temperatures.However,unexpected decline in quantum efficiency is observed after Mg-preflow treatment at room temperature.Our conclusions are drawn such that the efficiency decline is probably the result of different emission positions.Higher Mg doping concentration in the EBL after Mg-preflow treatment will make it easier for a hole to be injected into multiple quantum wells with emission closer to pGaN side through the（8-plane rather than the V-shape pits,which is not favorable to luminous efficiency due to the preferred occurrence of accumulated strain relaxation and structural defects in upper QWs closer to p-GaN.Within this framework,apparently disparate experimental observations regarding electroluminescence properties,in this work,are well reconciled.展开更多
We investigated the effects of handedness on developing latent cognitive response strategies according to situation variables. We used the findings of the block-wise Proportion Congruency (PC) effect in which the prop...We investigated the effects of handedness on developing latent cognitive response strategies according to situation variables. We used the findings of the block-wise Proportion Congruency (PC) effect in which the proportion of congruent trials in a given block modulates the compatibility effect in its block. The block-wise PC effect cannot be intentionally controlled. A Simon task with three different types of Proportion Congruency (PC) in a given block was used to measure the block-wise PC effects. This task was administered to 24 left-handed and 24 right-handed participants. The reaction time and error rates, consistent with previous studies, demonstrated that the block-wise PC effect was observed in left- and right-handers. Crucially, the block-wise PC effect was more pronounced in left- than right-handers, suggesting that left- and right-handers unintentionally apply different cognitive strategies in response to conflict resolution experiences.展开更多
Shale samples of Silurian Longmaxi Formation in the Changning area of the Sichuan Basin, SW China, were selected to carry out scanning electron microscopy, CT imaging, high-pressure mercury injection, low-temperature ...Shale samples of Silurian Longmaxi Formation in the Changning area of the Sichuan Basin, SW China, were selected to carry out scanning electron microscopy, CT imaging, high-pressure mercury injection, low-temperature nitrogen adsorption and imbibition experiments to compare the hydration characteristics of montmorillonite and illite, analyze the main factors affecting the water block removal of shale, and reveal the mechanisms of pore structure evolution during shale hydration. The hydration characteristics of shale are closely related to the composition of clay minerals, the shale with high illite content is not susceptible to hydration and thus has limited room for pore structure improvement;the shale with high montmorillonite is susceptible to hydration expansion and thus has higher potential of pore structure improvement by stimulation;the shale with high illite content has stronger imbibition in the initial stage, but insufficient diffusion ability, and thus is likely to have water block;the shale with high montmorillonite content has weaker imbibition in the initial stage but better water diffusion, so water blocking in this kind of shale can be removed to some degree;the shale reservoir has an optimal hydration time, when it is best in physical properties, but hydration time too long would cause damage to the reservoir, and the shale with high illite content has a shorter optimal hydration time;inorganic cations can inhibit the hydration of clay minerals and have stronger inhibition to illite expansion, especially K^(+);for the reservoir with high content of montmorillonite, the cation content of fracturing fluid can be lowered to promote the shale hydration;fracturing fluid with high K^(+) content can be injected into reservoirs with high illite content to suppress hydration.展开更多
基金supported by the National Natural Sciences Foundation of China(41871016)。
文摘Fences are one of the most effective measures to prevent and control wind-blown sand disasters,and the blocking effect of fences is largely determined by their porosity and height(H).This study employed wind tunnel experiments to measure wind velocities on both sides of wire mesh sand fences with porosities of 75%,63%,56%,36%and heights of 10,5 and 2 cm.The effects of porosity and height on the blocking effect of the fences were evaluated on the basis of velocity variability,flow field,and the wind velocity reduction coefficient.Results show that the smaller the porosity,the stronger the blocking effect.The fence with a porosity of 36%had the strongest windproof efficiency of 0.70 and longest protection range of 9 H,and thus showed the best applicability in preventing and controlling wind-blown sand disasters.The fence with a porosity of 56%showed a windproof efficiency of 0.31 and a protection range of 7 H,which could be considered for adoption.However,fences with porosities of 75%and 63%were not recommended to be adopted,because their windproof efficiency and protection range were very small.Overall,the higher the fence,the stronger the blocking effect.The highest fence(10 cm)had the longest protection range of 90 cm,which was the best in application.Nevertheless,the 5 and 2 cm fences were almost consistent with 10 cm fence in windproof efficiency,which was still suitable for wind and sand fixation.
基金financially supported by the National Natural Science Foundation of China (No.51504084)the Education Department of Fujian Province (No.JA15493)
文摘To research techniques for removing the water blocking effect caused by hydraulic applications in coal seams,the use of surfactants is proposed,based on the mechanics of the water blocking effect.Centrifugal experiments were used to validate the effects of using surfactants;the results show that after dealing with vacuum saturation with water,the volume of micropores decreases,which results in a larger average pore size,and the volume of transitional pores,mesopores,macropores and total pores increases.Based on the distribution of pore size,the operation mode of ‘‘water infusion after gas extraction,then continuing gas extraction" is recommended to improve the volume of coal mine gas drainage.When the reflectance of vitrinite in coal samples is less than 1,using the surfactants Fast T,1631,APG,BS can mitigate the damage caused by the water blocking effect.But when the reflectance of vitrinite is larger than 1.4,the damage caused by the water blocking effect can be increased.When the surfactant CMC is used in hydraulic applications,the capillary forces of coal samples are almost negative,which means the capillary force is in the same direction as the gas extraction.The direction of capillary forces benefits the gas flow.So,using CMC can play an active role in removing the water blocking effect.Centrifugal experiments confirm that using CMC can effectively remove the water blocking effect,which has a beneficial effect on improving the gas drainage volume.
基金supported by the Scientific Research Project Foundation of Jiangxi Provincial Education Department(GJJ08372)
文摘[ Objective] To investigate the blocking effects of spleen vaccine on vertical transmission of classical swine fever virus （CSFV） in sows. [ Method] Sows infected by CSFV were selected from three large-scale pig farms and they were randomly divided into group Ⅰ, group Ⅱ and control group. The sows in the group Ⅰ were vaccinated with CSF spleen vaccine at a 1.5 times normal dose per pig; those in the group Ⅱ were vaccinated with CSF spleen vaccine at a 2.0 times normal dose per pig; and those in the control group were vaccinated with cell vaccine at a 4.0 times normal- dose per pig. The CSF antigens of piglets were detected by enzyme-linked immunosorbent assay （ELISA）. [ Result] The antigen positive rate of piglets in the experimental group （18.5%） was significantly lower than that in the control group （48.1% ）. No significant difference was found be- tween the group Ⅰ and the group Ⅱ. [ Condmion] CSF spleen vaccine has good blocking effects on vertical transmission of CSFV in sows.
文摘Phenolic acids (PAs) are widely found in many daily consumed vegetables and fruits.The inhibitory effects of PAs on Nnitrosomorpholine (NMOR) formation in vitro undersimulated gastric juice condition were studied. The results showed that the inhibjtoryIX)tency of thirteen varieties of PAs differed greatly, which may be related to theirchemical structures; the blocking rate (BR) of different killds of PAs were as follows:caf feic acid, 92.5%; tannic acid, 90.0%; gallic acid, 86.8%; sinaPinic acid, 86.2%; ferulicacid, 8l.l%; chlorogenic acid, 69.4%; gentisic acid, 69.2%; syringic acid, 62.1%; protocatechuic acid, 56.0%; p-coumaric acid, 52.5%; vannilic acid, 35.4%; moreover,p-hydroxybenzoic acid and m-coumaric acid had the least blocking effect or even slightcatalyzing effect. The results also demonstrated that amounts of NMOR formed werenegatively correlated with molar ratio of PAs to nitrite and that the optimum pH forinhibition was between 2 and 3.
文摘BACKGROUND: It has been shown that although brain does not contain lining endothelial lymphatic vessel, it has lymphatic drain. Anterior lymphatic system of lymphatic vessel in brain tissue plays a key role in introducing brain interstitial fluid to lymphatic system; however, the significance of lymphatic drain and the effect on cerebral edema remains unclear. OBJECTIVE: To investigate the effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats. DESIGN: Randomized controlled animal study. SETTING: Institute of Cerebral Microcirculation of Taishan Medical College and Department of Neurology of Affiliated Hospital. MATERIALS: A total of 63 healthy adult male Wistar rats weighing 300-350 g were selected in this study. Forty-seven rats were used for the morphological observation induced by lymphatic drain and randomly divided into three groups: general observation group (n =12), light microscopic observation group (n =21) and electronic microscopic observation group (n =14). The rats in each group were divided into cerebral lymphatic block subgroup and sham-operation control subgroup. Sixteen rats were used for observing the effect of cerebral lymphatic block on cortical evoked potential, in which the animals were randomly divided into sham-operation group (n =6) and cerebral lymphatic block group (n =10). METHODS: The experiment was carried out in the Institute of Cerebral Microcirculation of Taishan Medical College from January to August 2003. Rats in cerebral lymphatic block group were anesthetized and separated bilateral superficial and deep cervical lymph nodes under sterile condition. Superior and inferior boarders of lymph nodes were ligated the inputting and outputting channels, respectively, and then lymph node was removed so as to establish cerebral lymphatic drain disorder models. Rats in sham-operation control group were not ligated the lymphatic vessel and removed lymph nodes, and other operations were as the same as those in cerebral lymphatic block group. Morphological changes of the brain and alterations of latency of cortical evoked potential were detected on the 1st, 2nd, 3rd, 5th, 7th, 10th and 15th days after operation under general, light microscope and electronic microscope observations. MAIN OUTCOME MEASURES: ① Cerebral morphological changes; ② latent changes of cortical evoked potential. RESULTS: A total of 63 rats were involved in the final analysis. ① Cerebral morphological changes: General observation showed that, for cerebral lymphatic block rats, the surface of brain was pale and full, and cerebral gyrus was wide and flattened sulci after cerebral lymphatic block; and cerebral tissue space prolongation, increased interstitial fluid, neuronal degeneration and necrosis, diffused phagocytes and satellitosis were observed under light microscope. Neuronal swell and necrosis, glial cell swell, apparent subcellular changes such as mitochondron were observed under electronic microscope. ② Latent changes of cortical evoked potential: As compared with sham-operation control group, latency of cortical evoked potential in cerebral lymphatic blockage group prolonged on the 5th day and 7th day after cerebral lymphatic block [(6.28±0.23), (6.97±0.35) ms; (6.23±0.22), (7.12±0.20) ms; P < 0.01]. CONCLUSION: ① Cerebral lymphatic block plays an important role in cerebral morphology, and may result in abnormality of sensitive impulse conduction and prolong latency of cortical evoked potential. ② Examination of cortical evoked potential is easy and convenient, so it is regarded as a key index for lymphatic disturbed cerebral injury.
文摘In this paper, blocking in response surface for fitting first order model incorporating neighbour effects has been investigated. The conditions for orthogonal estimation of the parameters of the model have been obtained. A method of constructing designs which ensures the constancy of variance of the parameter estimates of the model has also been given.
基金Supported by the National Key R&D Program of China under Grant Nos 2016YFB0400600 and 2016YFB0400601the State Key Program of the National Natural Science of China under Grant No 61334001+2 种基金the Key R&D Program of Jiangxi Province under Grant No 20165ABC28007the Natural Science Foundation of Jiangxi Province under Grant No 20151BAB207053the National Natural Science Foundation of China under Grant No 21405076
文摘In GaN-based green light-emitting diodes（LEDs） with and without Mg-preflow before the growth of p-Al GaN electron blocking layer（EBL） are investigated experimentally.A higher Mg doping concentration is achieved in the EBL after Mg-preflow treatment,effectively alleviating the commonly observed efficiency collapse and electrons overflowing at cryogenic temperatures.However,unexpected decline in quantum efficiency is observed after Mg-preflow treatment at room temperature.Our conclusions are drawn such that the efficiency decline is probably the result of different emission positions.Higher Mg doping concentration in the EBL after Mg-preflow treatment will make it easier for a hole to be injected into multiple quantum wells with emission closer to pGaN side through the（8-plane rather than the V-shape pits,which is not favorable to luminous efficiency due to the preferred occurrence of accumulated strain relaxation and structural defects in upper QWs closer to p-GaN.Within this framework,apparently disparate experimental observations regarding electroluminescence properties,in this work,are well reconciled.
文摘We investigated the effects of handedness on developing latent cognitive response strategies according to situation variables. We used the findings of the block-wise Proportion Congruency (PC) effect in which the proportion of congruent trials in a given block modulates the compatibility effect in its block. The block-wise PC effect cannot be intentionally controlled. A Simon task with three different types of Proportion Congruency (PC) in a given block was used to measure the block-wise PC effects. This task was administered to 24 left-handed and 24 right-handed participants. The reaction time and error rates, consistent with previous studies, demonstrated that the block-wise PC effect was observed in left- and right-handers. Crucially, the block-wise PC effect was more pronounced in left- than right-handers, suggesting that left- and right-handers unintentionally apply different cognitive strategies in response to conflict resolution experiences.
基金Supported by the Science and Technology Planning Project of Sichuan Province,China(2020YJ0135)National Natural Science Foundation of China(51874250)。
文摘Shale samples of Silurian Longmaxi Formation in the Changning area of the Sichuan Basin, SW China, were selected to carry out scanning electron microscopy, CT imaging, high-pressure mercury injection, low-temperature nitrogen adsorption and imbibition experiments to compare the hydration characteristics of montmorillonite and illite, analyze the main factors affecting the water block removal of shale, and reveal the mechanisms of pore structure evolution during shale hydration. The hydration characteristics of shale are closely related to the composition of clay minerals, the shale with high illite content is not susceptible to hydration and thus has limited room for pore structure improvement;the shale with high montmorillonite is susceptible to hydration expansion and thus has higher potential of pore structure improvement by stimulation;the shale with high illite content has stronger imbibition in the initial stage, but insufficient diffusion ability, and thus is likely to have water block;the shale with high montmorillonite content has weaker imbibition in the initial stage but better water diffusion, so water blocking in this kind of shale can be removed to some degree;the shale reservoir has an optimal hydration time, when it is best in physical properties, but hydration time too long would cause damage to the reservoir, and the shale with high illite content has a shorter optimal hydration time;inorganic cations can inhibit the hydration of clay minerals and have stronger inhibition to illite expansion, especially K^(+);for the reservoir with high content of montmorillonite, the cation content of fracturing fluid can be lowered to promote the shale hydration;fracturing fluid with high K^(+) content can be injected into reservoirs with high illite content to suppress hydration.
